the 93R is a newer design that's a bit more beefy than the 18c. However, both guns are as capable as the other.

Personally, I would avoid the 18c since it is an older design, the function may not work as well as the 93R.

Plus, the 93R is designed as a submachine gun first, where as the 18C is a pistol with automatic. You can get inexpensive steel folding stocks for the 93R. The burst function is a huge ammo saver, and the NS2 engine is very fun to use. I'd pick that as the better bugout gun over the 18c.

If you just want something that will shoot and help you get to your primary. The semi-automatic pistols are a better choice in terms of stability.